Growth of the medicinal plants is affected by the biological (biotic) and physical (abiotic) factors. The physical factors mainly consist of climate, which accounts for greater variation in crop yields. Hence it is important to remove all the physical factors limiting plant growth resulting in substantial increase in the yield of crops per unit area per unit time. Photosynthetic efficiency of crop plants should be stimulated for full utilization of all biological and physiological reserves in the plants. Higher crop production is possible by increasing the biological solar energy conversion.